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From: gregkh@linuxfoundation•org (Greg Kroah-Hartman)
To: linux-arm-kernel@lists•infradead.org
Subject: Possible regression between 4.9 and 4.13
Date: Wed, 30 Aug 2017 08:45:37 +0200	[thread overview]
Message-ID: <20170830064537.GA8856@kroah.com> (raw)
In-Reply-To: <20170830063623.GA16076@wunner.de>

On Wed, Aug 30, 2017 at 08:36:23AM +0200, Lukas Wunner wrote:
> On Tue, Aug 29, 2017 at 05:51:38PM +0200, Greg Kroah-Hartman wrote:
> > On Tue, Aug 29, 2017 at 05:34:56PM +0200, Lukas Wunner wrote:
> > > On Tue, Aug 29, 2017 at 04:47:25PM +0200, Greg Kroah-Hartman wrote:
> > > > On Tue, Aug 29, 2017 at 03:38:52PM +0200, Lukas Wunner wrote:
> > > Is 0xffffffff not a valid value to be stored in and read from mmio space?
> > 
> > For a specific register, doubtful
> 
> Well, "doubtful" means you don't know for sure.
> 
> It's fine to check for "all ones" as a heuristic if that's not a valid
> value for the register read, however a hotplug notification is a
> *definitive* indication the hardware is gone.
> 
> I you seem to prefer forgoing a *definitive* indication for a mere
> heuristic, that doesn't make sense from my point of view.

I still don't know what you are arguing about here.  The _driver_ knows
if a specific read allows all ones as a valid return value.  If it
isn't, then the driver knows the device is now gone.  It's that simple,
don't do that type of check if all ones is a valid read.

And that's not what is happening here anyway, so again, what is this
discussion about?

Unless there's something specific we can do here for the xhci driver, I
think this thread is dead until someone determines what is going wrong
with the hardware the original reporter posted about.

greg k-h

  reply	other threads:[~2017-08-30  6:45 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-22 17:34 Possible regression between 4.9 and 4.13 Mason
2017-08-23  6:07 ` Felipe Balbi
2017-08-23  7:51   ` Mathias Nyman
2017-08-23  9:18     ` Mason
2017-08-23  9:31     ` Mason
2017-08-23 11:11       ` Mathias Nyman
2017-08-23 11:54         ` Mason
2017-08-23 12:41           ` Mason
2017-08-23 14:30             ` Mason
2017-08-28  8:39               ` Mathias Nyman
2017-08-28 14:40                 ` Mason
2017-08-29 13:28                   ` Mathias Nyman
2017-08-29 13:38                     ` Lukas Wunner
2017-08-29 14:47                       ` Greg Kroah-Hartman
2017-08-29 15:34                         ` Lukas Wunner
2017-08-29 15:51                           ` Greg Kroah-Hartman
2017-08-30  6:36                             ` Lukas Wunner
2017-08-30  6:45                               ` Greg Kroah-Hartman [this message]
2017-08-29 23:53                     ` Lukas Wunner
2017-08-30  6:02                       ` Greg Kroah-Hartman
2017-08-30  8:55                         ` Mason
2017-08-30  9:06                           ` Greg Kroah-Hartman
2017-08-31  9:39                             ` Mason
2017-08-31 11:40                               ` Mathias Nyman
2017-08-30  9:07                           ` Ard Biesheuvel
2017-08-30  9:22                             ` Greg Kroah-Hartman
2017-08-30  9:37                             ` Mason
2017-08-31  9:17                               ` Mason
2017-08-31 11:38                                 ` Mathias Nyman
2017-08-23 10:19     ` Mason

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